Control system



Nov. 9, 1937.

CONTROL SYS TEM Filed Jan. 4, 1936 L. R. ALLISON 2 Sheets-Sheet l Fig.5.

I lNvEN roR Lerlze HAUL/ 012 ATTO R N EY HIS Patented Nov. 9, 1937UNITED STATES PATENT OFFICE CONTROL SYSTEM Application January 4, 1936,Serial No. 57,572

4 Claims.

My invention relates to control systems, and particularly to controlsystems for electrical relays which are slow-releasing in character.

A feature of my invention is the provision of novel and improvedapparatus for governing the operation of a relay characterized by beingprovided with a predetermined slow-release period and which relay isenergized in multiple with another device possessing inductance. Otherfeatures and advantages of my invention will appear as the specificationprogresses.

I will describe several forms of apparatus embodying my invention, andwill then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a diagrammatic view of one formof apparatus embodying my invention, and Fig. 2 is a diagrammatic viewof a second form of apparatus embodying my invention. Figs. 3 and 4 arediagrammatic views of two different forms of circuits and apparatusshowing applications of my invention to railway signal systems.

In the following description, reference is made "V to the accompanyingdrawings in which like reference characters designate similar parts.

In Fig. 1, a source of current such as a battery 2 is connected acrosstwo control wires 3 and 4, the polarity of the battery being asindicated by the plus and minus signs. A circuit controlling contact 5is interposed between the battery and the control wires for governingthe supply of current to the circuit. As here shown, the contact 5 islocated between the positive terminal of battery 2 and the control wire3, the contact 5 being operable to a closed position which is indicatedby the solid line in the drawings, or to an open position which isindicated by a dotted line.

Two direct current relays 5 and l are controlled by current supplied bythe battery 2 over the contact 5 by virtue of having their operatingwindings connected across the control wires 3 and 4 in multiple. To beexplicit the left-hand terminal f the winding of relay 5 is connectedwith wire 3 over wire 29, and its right-hand terminal is connected withwire 4 over wire hi, asymmetric unit 8 to be referred to later, and wireF5. The left-hand terminal of the winding of rela l is connected withwire 3 over wire 18, and its rigl1thand terminal is connected with wire4 over wire I1, asymmetric unit 9, and wire 18. These asymmetric units 8and 9 may be of any one of several diflerent forms such as, for example,the well-known copper oxide rectifier, and each is disposed with itsforward or low resistance direc- 55 tion toward the control wire 4 whichwire is connected with the negative terminal of battery 2. The relay 6is provided with a circuit controlling armature l0 capable of makingengagement with a front contact II when the relay is energized andfalling away therefrom when the relay is deenergized. In like manner therelay l is provided with a circuit controlling armature l2 adaptable ofmaking engagement with a front contact l3 when the relay is energizedand to fall out of engagement therewith when the relay is deenergized.These contacts Hl-l| and |2|3 of relays 6 and 1, respectively, may beused to govern other circuits as desired. The relays 5 and I are eachslow-releasing in character and each is preferably provided with aparticular predetermined slow-release period in accordance with what maybe required to give proper operation of the circuit controlled by thatrelay. In other words, the slow-release periods for relays 6 and '1 maybe unequal in duration. For example, the release period of relay 6 maybe of the order of one second and that of relay 1 may be of the order oftwo seconds. It follows that when contact 5 occupies its closedposition, current flows from battery 2 through the windings of the tworelays 6 and l in multiple and the armatures of the two relays arepicked up, the asymmetric units 8 and 9 not impeding the flow of currentsince each unit is disposed with its forward direction toward thenegative terminal of the battery, but that when contact 5 is operated toits open position, current is removed from the windings of the tworelays and both relays are deenergized and the armature of each relay isreleased at the end of the particular release period of the associatedrelay.

It is sometimes desirable to periodicaily operate contact 5 between itsopen and closed positions at a rate sufiicient to allow one of therelays, say relay 6, to release during the open period and not relay 1,and then at other times to operate contact 5 at a rate such that bothrelays are released during the open period. Heretoiore the operation oftwo or more slow-release relays with different retardations wascomplicated because the retardation of one relay was not independent ofthe electrical characteristics of the other relay operating in multiplewith it. That is, without asymmetric units interposed in the circuitconnections, if contact 5 were moved to its open position there would bea flow of current from the winding of one relay to the winding of theother relay due to the stored inductive energy. Assuming the polarity tobe as indicated in Fig. 1 and that the asymmetric units 8 and 9 areomitted from the circuit and contact 5 is moved .to its open position,current will tend to flow from the winding of relay 6 due to the voltageof self-inductance over a circuit traced from the righthand terminal ofthe winding. of relay 6, wires I I and I5, control wire I, wires It andII, winding of relay I, wire I6, control wire 3, and wire 28 to theleft-hand terminal of the winding of relay 6. In a similar manner, thevoltage of self-inductance of relay I will tend to cause current to flowfrom the righthand terminal of the winding of relay I over wires I'I,I8, 8, I5 and I I, winding of relay 6, wires 20, 3 and It to theleft-hand terminal of the winding of relay 1. Of course, if thecharacteristics of the two relays 6 and I are exactly alike, thevoltages of self-inductance will cancel each others effects, but sinceit is impracticable and, as stated hereinbefore, in any casesundesirable to have the relays of like charac teristics, the releasetime of each relay will be effected by the change of energy between therelays. It is clear that with apparatus constructed in accordance withmy invention, the asymmetric unit 9 is effective to block the flow ofany gize the two devices in multiple.

current caused by the voltage of self-inductance of relay 6, and theasymmetric unit 8 is effective to block any flow of current caused bythe voltage of self-inductance of relay I, and hence the release periodsof the relays are independent of each other.

In Fig. 2, the battery 2 is connected with control wires 3 and d overthe contact 5 the same as in Fig. 1. Also, the relay I is connectedacross these control wires with the asymmetric unit 9 interposed in theconnection the same as in Fig. l. A winding I9 is connected across thecontrol wires for receiving energizing current in multiple with thewinding of relay TI. This winding I9 may be included in any device whichit is desired to operate by current from battery 2 over contact 5. Thesignificant fact about the winding It as far as the presentapplicationis concerned is that it possessesinductance. It is clear thatwith contact 5 closed, current is supplied through winding I9 and to thewinding of relay 'I to ener- When the contact 5 is operated to the openposition, the voltage of self-inductance of winding I9 is ineffective tocause current to flow through the winding of relay I in a directionreverse to the direction of the energizing current due to the asymmetricunit 9, and hence the release period of relay I is independent of theeifect of the voltage of selfinductance of winding IQ. It is apparentthat should it seem desirable to do so, an asymmetric unit may beinserted in the connection of winding I9 with its low resistancedirection toward the control wire #1 the same as the unit 8 isinterposed in the connection of relay 6 of Fig.1, and when the apparatusof Fig. 2 is thus constructed, a flow of current back through winding I9 due to the voltage of self-inductance of relay I would be avoided. 7

Many places where my invention will be useful will suggest themselves.In Fig. 3, the invention is applied to a code wayside signal system forrailways and wherein certain of the control relays are provided withpredetermined slow-release periods for proper operation of the system. Astretch of railway track'is formed into successive track sections by theusual insulated rail joints,

there being only one section IT together with the ends of adjacentsections shown in the dran ings for the sake of simplicity, The tracksection 1 IT is providedwith a track circuit consisting of a currentsource connected across the rails at one end of the section and a relayconnected across the rails at the other end of the section. Theimmediate source of current for the track circuit of section IT is thesecondary winding 2i of a track transformer TI the primary winding 22 ofwhich is supplied with coded alternating current over wire 49 and a codeselection network to be referred to hereinafter. The track relay TR is aquick acting direct current relay the operating winding of'which issupplied with rectified current through a rectifier 23 the inputterminals of which rectifier are connected across a reactor 24interposed in a tuned circuit including a condenser 25 and the secondarywinding 26 of a transformer T2 whose primary winding 2'5 is, in

turn, connected across the rails of section IT.

The tuned circuit consisting of the elements 28, 25 and 26 is tuned toeffectively pass current of the track circuit and which in this instanceis preferably an alternating current of cycles per second. It followsthat as long as the rails of section IT are supplied with alternatingcurrent of 100 cycles per second, the relay TR is energized and itscontact members 28 and 29 are lifted into engagement with front contacts36 and 3 I, respectively, but that during intervals no such current issupplied to the rails of the section IT, the relay TR is released andits contact members 28 and 29 drop into engagement with'back contacts 32and 33, respectively. As will appear hereinbefore the alternatingcurrent supplied to the track circuit of section IT is under certaintrafiic conditions coded at one rate which rate I shall assume to be ofcycles per minute, and under other traffic conditions it is coded at asecond,

rate which rate I shall assume to be of 80 cycles per minute. Since thetrack relay TR is a quickacting relay, it is a code following relayoperating its contact members 28 and 29 at the rate corresponding to thecode of the current supplied to the section IT.

The apparatus for section IT includes a code transmitter and a codeselection network for supplying current to the track rails of thesection in the rear, that is, the section to the left of section IT inFig. 3. immaterial and, as here shown, the operating winding of a codetransmitter CT is continuously supplied with current from any convenientsource of current such as a generator not shown. The code transmitter CToperates two coding contact members I35 and 80, the arrangement beingsuch that the code contact member I80 engages a stationary contact 34 atthe rate of 180 times per minute and the code contact member 80 engagesa stationary contact 35 at the rate of 80 times per minute. A circuitconnection may be traced from the BX terminal of the source ofalternating current provided for section IT over the code contactI8Il34, front contact 36 of a relay ZR to be referred to later, frontcontact 3i of a'relay H to also be referred to later, primary winding 38of a track transformer T3 and to the CX terminal of the current source,the secondary winding 39 of transformer T3 being in turn connectedacross the rails of the section to the rear of section IT. Anothercircuit connection may be traced fromthe BX terminal of the source ofcurrent over the code contact 80-45, back contact 6 of relay I-I,primary winding 38 of transformer T3 and to the other terminal: CX ofthe current source. Thus, under trafiic conditions to cause both relaysZR and H to be picked up, alternating current of 180 code is supplied toThe type of code transmitter is the rails of the section in the rear,and under traffic conditions that permit relay H to be released, thecurrent is of the 80 code. The apparatus for the section in advance ofthe section IT, that is, the section to the right in Fig. 3, is providedwith code transmitting apapratus for sup plying coded alternatingcurrent over wire 49 and the primary winding 22 of transformer T in thesame manner as just described for the apparatus of section IT.

The code following track relay TR governs a group of control relaysconsisting of relays ZR, H, AJ and FSA in a manner to be now pointedout. With relay TR operated at either the 180 or 80 code, its contactmember 28 periodically reverses the flow of direct current from a sourcewhose terminals are designated B and C in the primary winding 4| of adecoding transformer DT as will shortly be described, thereby inducingan alterhating electromotive force in the secondary winding 42 oftransformer DT, the frequency of which electromotive force correspondsto the code at which the relay TR is operated. The decoding relay AJ isenergized through a rectifier 43 and a transformer T4 by theelectromotive force induced in the secondary winding 42 of the decodingtransformer DT, and is effectively energized to pick up its contactfingers 50, and 52 under the 180 code only, since the circuit consistingof secondary winding 42, condenser 44, and primary winding 45 oftransformer T4 is tuned to pass current at the frequency correspondingto the 180 code only.

Starting from a period when no current is supplied to the rails ofsection IT, relay TR is down, all control relays are deenergized, andassuming that current of 180 code is supplied to the rails of sectionIT, on the first operation of relay TR. its contact 29-3I is closed withthe result that current is supplied to the winding of relay FSA over acircuit traced from B battery terminal, contact 29-3 I, wire 59, windingof relay FSA, asymmetric unit 46, wire 6|! and to the C battery terminaland that relay is picked up. It is to be noted that in accordance withmy invention, an asymmetric unit 46 is interposed between the winding ofrelay FSA and the wire 60 leading to the C terminal of the currentsource. On the next operation of relay TR contact 29-33 is closed, andthe relay H is energized over a simple circuit which includes B batteryterminal, contact 29-33, a front contact 41 of relay FSA since the relayFSA is provided with a slow release period by virtue of a resistor 48connected across the terminals of its operating winding, winding ofrelay H, wire 60 and to C battery terminal. On the third operation ofrelay TR, the second closing of its contact 293| is effective to supplycurrent to the lower winding 66 of relay ZR, the circuit including Bbattery terminal, contact 29-3l, back contact 50 of relay AJ, winding66, front contact 54 of relay H which is slow-releasing in character,and to C battery terminal. Under the 180 code, the relay AJ is picked upafter a few operations of relay TR subsequent to the picking up of relayZR since with front contact 6! of relay ZR closed current is suppliedfrom B battery terminal over front contact 61 of relay ZR, contact 28-30of relay TR, top portion of winding 4| of transformer DT and to Cbattery terminal during one operation of relay TR, and then is suppliedto the lower portion of winding 4| during the operation of relay TR thatcloses its contact 28-32. Current thus supplied to the two portions ofwinding 4| induces an electromotive force in winding 42 of transformerDT which electromotive force is passed by the tuned circuit consistingof elements 42, 44 and 45 and rectified current is supplied to thewinding of relay AJ through rectifier 43. With relay AJ picked up therelay ZR is retained energized by code impulses supplied from B batteryterminal over contact 293| of relay TR, front contact 5| of relay AJ,front contact 56 of relay ZR, top winding 53 of the relay, asymmetricunit 58 and thence over wire 60 to the C battery terminal. The relay ZRis provided with a predetermined slow-release period by virtue of aresistor 51 connected across the terminals of its top winding 53. It isto be noted that in accordance with my invention the asymmetric unit 58is interposed between the top winding 53 of relay ZR and the C batteryterminal. In the event the relay TR is operated at the 80 code, therelays FSA and. H will be picked up in a manner similar to thatdescribed above for the 180 code current, but the relay AJ remains down.Under this condition, the relay ZR. is energized by code impulses fromthe B battery terminal over contact 29-33 of relay TR, front contact 55of relay FSA, back contact 5| of relay AJ, front contact 56 of relay ZR,top winding 53 of that relay, asymmetric unit 58, and to the C terminalover the wire 80.

It is to be noted that under the 180 code the two relays FSA and ZR areenergized in multiple, their operating windings being connected betweenwire 59 leading to the contact 3| of relay TR, and wire 60 leading tothe C terminal of the current source. The asymmetric units 46 and 58 areeffective, however, in preventing any interchange of energy betweenthese two relays due to voltage of self-inductance during the openperiods of contact 29-3| with the result each relay FSA and ZR isoperated independent of the other. These two relays FSA and ZR are soconstructed and adjusted as to be provided with different predeterminedslow release periods in order to provide a desired protection for signalsystems of the type here involved. This protection neednot be heredescribed since it forms no part of my invention, the significant thingbeing that with the circuits and apparatus constructed in accordancewith my invention, the asymmetric units 45 and 58 assure properoperation of the two relays FSA and ZR which, although having differentelectrical characteristics, operate independently of the other whenconnected in multiple.

Traflic through this section IT is governed by a signal SI which is hereshown as a position light signal. The indications of signal SI areselectively controlled by the group of control relays in a manner whichwill be obvious from the drawings and it is deemed unnecessary to tracethe signal operating circuits in detail.

In Fig. 4, apparatus embodying my invention is appliedv to another formof apparatus and circuits for a code wayside signal system. In thislatter system, a railway is divided into successive track sections ofwhich only the one section IT is shown the same as in Fig. 3. The tracksection IT of Fig, 4 is provided with a source of coded alternatingcurrent and a code following track relay TR the same as in Fig. 3 exceptfor the fact that the code selection network is modified somewhat aswill be understood by an inspection of the drawings. In Fig. 4, thegroup of control relays include the relays FSA, H and AJ, the same as inFig. 3, together with a relay designated by the reference character BSA.The decoding relay AJ of Fig. 4 is effectively energized through themedium of the decoding transformer D'I, tuned circuit including elements42,, 44 and 45, and a rectifier 43 when the relay TB is operated by 180code current the same as described in Fig. 3. The relay FSA isperiodically energized over the contact 29-3i of relay TR and the relayBSA is periodically energized over the contact 29-33 of relay TR, afront contact 6! of relay FSA being interposed in the circuit for therelay BSA. Hence both the relays FSA and BSA are picked up whenever therelay TR is operated under either the 130 or code. With relay BSA pickedup, the relay H receives an energizing impulse each time contact 283E3of relay TR is closed over a circuit including the B terminal of thecurrent source, contact 283il, asymmetric unit 62, front contact 63 ofrelay BSA, winding of relay H, and hence to the C battery terminal. Withrelay H once picked up, it also receives current over a stick circuitextending from the B battery terminal, resistor '64, front contact 65 ofrelay H, front contact 53 of relay BSA, winding of relay H and to the 0battery terminal. The relay E is provided with a predeterminedslow-release period for assuring proper operation of the system. It isto be noted that the winding of relay H and the primary winding of thedecoding transformer DT are energized in multiple. The assymmetric unit62 is effective, however, to prevent the voltage of self-inductance ofthe primary winding ll from causing the release of the relay H duringthe pick-up interval of that relay and also prevents the voltage ofself-inductance from varying its slow-release period.

Although I have herein shown and described only certain forms ofapparatus embodying my invention, it is understood that various changesand modifications may be made therein within the scope of the appendedclaims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a railway track formed into an insulated section,means to supply coded alternating current to the rails of said section,a code following relay receiving current from the rails of said sectionfor operating a circuit'controlling contact member, two control relayseach provided with a particular predetermined slowrelease period, saidtwo relays proportioned differently to possess different slow releaseperiods, circuit means including a direct current source and saidcontact member for supplying code impulses of current to the windings ofsaid relays in multiple, two asymmetric units one for each relay andeach unit interposed in series with the winding of the associated relayand said units both disposed with their forward direction toward thenegative terminal of said direct current source whereby each of saidrelays is operated at its particular release period, and signaling meansfor governing trafiic through said section con trolled by said relays.

2. In combination, a railway track formed into an insulated section,means to supply coded alternating current to the rails of said section,a code following relay receiving current from the rails of said sectionfor operating a circuit controlling contact member, decoding meansincluding a decoding transformer, a control relay having a predeterminedslow-release period, circuit means including a direct current source andsaid contact member for supplying code impulses of current to theprimary winding of said transformer and to a winding of said controlrelay for energizing the two windings in multiple, said two windingsproportioned differently to possess different electrical characteristicsas required for said transformer and said relay, and asymmetric unitinterposed in series with the winding of said relay and disposed withits high resistance direction toward the positive terminal of saidtransformer winding whereby the voltage of self-inductance of thetransformer winding is ineifective during the open periods of thecontact member to influence said control relay, and signaling means togovern traffic through said section governed by said control relay.

3. In combination, a railway track formed into an insulated section,means to supply coded alternating current to the rails of said section,a code following relay receiving current from the .rails. of the sectionfor operating a circuit contact member, control means including awinding, a control relay having a predetermined slow r lease period,circuit means including a direct current source and said contact memberfor supplying code impulses of current to the winding of said controlmeans and to'a winding of said control relay for energizing saidwindings in multiple, said two windings proportioned differently topossess different electrical characteristics as required for saidcontrol means and said relay, an asymmetric unit interposed in' serieswith the winding of said relay and disposed with its. forward directiontoward the negative terminal of said direct current source whereby saidrelay is released independent of the voltage of self-inductance of thewinding of said control means when the contact member is not operated,and two circuits one governed by said control means and the othergoverned by said control relay.

4. In combination, a railway track formed into an insulated section, atrack circuit for the section including a current source and the windingof a track relay, said relay provided with a circuit controlling contactmember operable to one position when the winding is energized and to asecond position when the winding is deenergized, two control relaysprovided with different predetermined slow release periods, circuitmeans including a direct current source and said contact member in itssaid one position for supplying current to the windings of the controlrelays in;

multiple, said. two windings proportioned differently as required toeffect said different release periods for said relays, two asymmetricunits one for each control relay and each unit interposed in series withthe winding of the associated relay and said units both disposed withtheir forward direction toward the negative terminal of said directcurrent source whereby each control relay is released at the end of itsrelease period independent of the voltage of self-inductance of thewinding of the other control relay when said member is operated to itssecond position, and two circuits one governed by one control relay andthe other governed by the other control relay.

LESLIE R. ALLISON.

